Engineering plastics are widely used in several high performance applications due to their specific properties like thermal stability, impact resistance and tensile strength. Engineering plastics do, however, also have disadvantages, such as difficult processing, high water absorption and high flammability.
Engineering plastic are thermoplastics which have mechanical, chemical and thermal properties, maintain dimensional stability, and are suitable for conditions under high impact, heat or moisture. They include acetals, polycarbonates (PC), polyphenylsulfides, polysulfones, modified polyphenylene oxides, polyimides, polyamides (PA), polybutylene terephthalate (PBT), acrylonitrile-butadiene-styrene (ABS), liquid crystal polymers (LCP), ethylene vinylacetate copolymer (EVA) and other plastics used for engineering purposes.
In order to improve the flame retardancy of engineering plastics halogen- or phosphorus containing organic compounds or red phosphorus is used. These additives do, however, have some serious disadvantages. Thus in the event of a fire, toxic and corrosive gases are released that can harm both people and environment. In addition the mechanical properties and processability of the engineering plastics are reduced. Also non-toxic additives such as aluminium trihydrate, magnesium hydroxide and glass fibres are used to improve flame retardancy of engineering plastics, but even though not toxic they can harm the mechanical properties and the processability of engineering plastics.
In order to maintain the mechanical properties, additives like fillers such as talc or wollastonite or fibres such as glass fibres or carbon fibres, are added to the compound for producing engineering plastics, but the incorporation of these materials gives rise to other negative effects, one such disadvantage being a high compound viscosity giving a reduced processing speed. The optimisation of compound properties and processing behaviour and the performance of final article made from these engineering plastic compounds are therefore very difficult.